{"id":"CVE-2026-23230","title":"smb: client: split cached_fid bitfields to avoid shared-byte RMW races","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: split cached_fid bitfields to avoid shared-byte RMW races\n\nis_open, has_lease and on_list are stored in the same bitfield byte in\nstruct cached_fid but are…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-821"],"vendor":"Linux","product":"Linux","affected":["Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < 569fecc56bfe4df66f05734d67daef887746656b","Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < 4386f6af8aaedd0c5ad6f659b40cadcc8f423828","Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < 3eaa22d688311c708b73f3c68bc6d0c8e3f0f77a","Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < c4b9edd55987384a1f201d3d07ff71e448d79c1b","Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < 4cfa4c37dcbcfd70866e856200ed8a2894cac578","Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < ec306600d5ba7148c9dbf8f5a8f1f5c1a044a241","Linux 6.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:06:47.736511Z"},"published":"2026-02-18","updated":"2026-10-19","sourceUpdated":"2026-10-19T18:35:39.300Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23230","references":[{"url":"https://git.kernel.org/stable/c/569fecc56bfe4df66f05734d67daef887746656b"},{"url":"https://git.kernel.org/stable/c/4386f6af8aaedd0c5ad6f659b40cadcc8f423828"},{"url":"https://git.kernel.org/stable/c/3eaa22d688311c708b73f3c68bc6d0c8e3f0f77a"},{"url":"https://git.kernel.org/stable/c/c4b9edd55987384a1f201d3d07ff71e448d79c1b"},{"url":"https://git.kernel.org/stable/c/4cfa4c37dcbcfd70866e856200ed8a2894cac578"},{"url":"https://git.kernel.org/stable/c/ec306600d5ba7148c9dbf8f5a8f1f5c1a044a241"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23230.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-23230"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2440658"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-23230"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23230"},{"url":"https://lore.kernel.org/linux-cve-announce/2026021808-CVE-2026-23230-8d0e@gregkh/T"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00278,"epssPercentile":0.20142,"scores":{"cna":8.8,"vendor":6.3},"ingestedAt":"2026-10-16T17:24:46.641Z","slug":"CVE-2026-23230","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: split cached_fid bitfields to avoid shared-byte RMW races\n\nis_open, has_lease and on_list are stored in the same bitfield byte in\nstruct cached_fid but are updated in different code paths that may run\nconcurrently. Bitfield assignments generate byte read–modify–write\noperations (e.g. `orb $mask, addr` on x86_64), so updating one flag can\nrestore stale values of the others.\n\nA possible interleaving is:\n    CPU1: load old byte (has_lease=1, on_list=1)\n    CPU2: clear both flags (store 0)\n    CPU1: RMW store (old | IS_OPEN) -> reintroduces cleared bits\n\nTo avoid this class of races, convert these flags to separate bool\nfields.\n\n## Affected\n\n- `Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < 569fecc56bfe4df66f05734d67daef887746656b`\n- `Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < 4386f6af8aaedd0c5ad6f659b40cadcc8f423828`\n- `Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < 3eaa22d688311c708b73f3c68bc6d0c8e3f0f77a`\n- `Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < c4b9edd55987384a1f201d3d07ff71e448d79c1b`\n- `Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < 4cfa4c37dcbcfd70866e856200ed8a2894cac578`\n- `Linux >= ebe98f1447bbccf8228335c62d86af02a0ed23f7 < ec306600d5ba7148c9dbf8f5a8f1f5c1a044a241`\n- `Linux 6.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 10 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23230.json)","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":225163,"id":"CVE-2026-23230","ts":1792438846726,"field":"cvss","old":"6.3","new":"8.8"},{"seq":225162,"id":"CVE-2026-23230","ts":1792438846726,"field":"severity","old":"medium","new":"high"},{"seq":223590,"id":"CVE-2026-23230","ts":1792238328495,"field":"cvss","old":"8.8","new":"6.3"},{"seq":223589,"id":"CVE-2026-23230","ts":1792238328495,"field":"severity","old":"high","new":"medium"}]}